The present invention utilizes aspects of Applicant's earlier inventions, some of which are repeated herein. U.S. Pat. Nos. 6,362,554; 6,753,682 and 6,911,166, which are hereby incorporated by reference, further disclose some of these concepts.
An example of a conventional motor 1 is shown in FIG. 1. The motor 1 includes a base 2 which is usually made from die cast aluminum, a stator 4, a shaft 6, bearings 7 and a disc support member 8, also referred to as a hub. A magnet 3 and flux return ring 5 are attached to the disc support member 8. The stator 4 is separated from the base 2 using an insulator (not shown) and attached to the base 2 using a glue. Distinct structures are formed in the base 2 and the disc support member 8 to accommodate the bearings 7. One end of the shaft 6 is inserted into the bearing 7 positioned in the base 2 and the other end of the shaft 6 is placed in the bearing 7 located in the hub 8. A separate electrical connector 9 may also be inserted into the base 2.
Each of these parts must be fixed at predefined tolerances with respect to one another. Accuracy in these tolerances can significantly enhance motor performance.
An important factor in motor design is the lowering of the operating temperature of the motor. Increased motor temperature affects the electrical efficiency of the motor and bearing life. As temperature increases, resistive loses in wire increase, thereby reducing total motor power. Furthermore, the Arrhenius equation predicts that the failure rate of an electrical device is exponentially related to its operating temperature. The frictional heat generated by bearings increases with speed. Also, as bearings get hot they expand, and the bearing cages get stressed and may deflect, causing non-uniform rotation and the resultant further heat increase. One drawback with existing motor designs is their limited effective dissipation of the heat, and difficulty in incorporating heat sinks to aid in heat dissipation. In addition, in current motors the operating temperatures generally increase as the size of the motor is decreased.
Electromagnetic devices used in electrical products may need to be cooled to remove heat generated by operation of the device. It is well known that a fluid in the environment of the device can be used to aid cooling. As an example, a method of cooling a motor is to include a fan on the motor shaft. The fan then blows air past the motor. Air, however, has a fairly low heat capacity, and thus cannot carry away as much heat as is sometime generated by the motor. Also, in some applications there is no place to mount a fan. Other fluids, and liquids in particular, typically have a high enough heat capacity that they can be used to carry away heat. For example, a water pump driven by a motor uses the water to cool the pump. The problem with liquids, however, is getting them in contact with hot motor surfaces without damaging the motor, and then collecting them to carry them away. Thus, a need exists for an improved motor that includes an effective and practical way of using a liquid to carry heat away from the motor. Also, a need exits for improved methods of cooling other electromagnetic components.
Also, there are times when the heat generated by operation of the electrical device, such as a motor, could be put to a beneficial use if there were a way to confine a fluid used in a heat transfer relationship with the device so that it could be directed to a point of desired use. Thus, if liquids or gasses could be channeled in such a way that they picked up heat from an electromagnetic device without damaging the device, and then carried that heat to a place where the heat was desired, that would be a great benefit.
One difficulty encountered in the design of electrical components is that various components need to withstand exposure to solvents and particulates. The environmental agents can corrode the conductors or inductors in the component. In pumps used for movement of corrosive agents, this can be a particular problem. In hybrid electric vehicles where the motor or generator resides inside of the transmission housing, stray metallic debris generated from the transmission gears may be thrown into the windings, damaging them to the point that the device no longer works.